Modeling and implementing fire safety for nuclear power plants (NPP) under NFPA 805 is an expensive proposition. Due to the complexity of fire phenomena, the multiple methods/tools needed, and the numerous potential ignition sources, it is complex to develop, maintain, and use accurate fire models. The Fire Risk Investigation in 3D (FRI3D) software was initially developed as part of the research for enhanced fire analysis under Light Water Reactor Sustainability (LWRS) program. The goal of this software has two parts: (1) provide industry with a tool to simplify the process for developing and using detailed fire models; (2) provide a back-end for future enhanced fire analysis and possible extension to dynamic probabilistic risk analysis models.
Fire models are constructed using various tools and methods, such as FRANX, CAFTA, CFAST, Heat Soak, THIEF, etc. Maintenance of these models can be time consuming as changes to the models or scenarios can require extensive effort across multiple platforms to reassess changes. The FRI3D software imports existing plant models and then combines required tools and methods in a 3D visualization environment. This coupled approach automates many of the tasks under one system, reducing the overall maintenance costs and human errors for fire modeling. FRI3D platform also maintains all necessary information in one place allowing the analyst to evaluate scenarios without accessing numerous plant drawings and databases. FRI3D will give the analyst direct access (built in) to the industry approved fire modelling codes and methods and is effectively a one stop shop.
The use of FRI3D by NPP operators, regulators and engineering consultancy firms is expected to lead to the enhancement of fire PRA, increased safety, and reduced operating costs. The FRI3D platform can also store all necessary information (drawings, databases etc.) in one place allowing the analyst to efficiently develop and evaluate scenarios. The tool would help both regulators and licensees demonstrate how the operating fire risk compares to regulatory requirements.
The main objectives of Phase I of this project was to deliver a minimum viable version of FRI3D, ready to be used in conjunction with Plant Data Management System (PDMS), FRANX and Consolidated Fire and Smoke Transport Model (CFAST), and to conduct an industry value study. Many additional features were developed to facilitate and speed up the construction and manipulation of the NPP model and fire compartment in 3D and to provide real-time visualization of failed items, failure times, and all the necessary outputs to inform the analyst and facilities the generation of the fire scenarios. In addition, developments were made to account for secondary combustibles and to accommodate new changes and features of the latest CFAST version. Following NUREG-1934, Appendices A and B, cabinet fire scenarios were modeled and used to verify and validate the CFAST output produced through FRI3D, to evaluate the usability, and to estimate the time-cost benefits against the conventional workflow.